Relationship between the tonic elevator mandibular activity and the vertical dimension during the states of vigilance and hypnosis.

The variation of the tonic EMG elevator mandibular activity was studied as well as the consequent variation of the vertical dimension in two different experimental states: those of vigilance and hypnosis. In the state of vigilance, normal values of tonic EMG activity were recorded and a space of inocclusion (X = 2.22 mm) coincident with the postural mandibular position. Under hypnosis a significant reduction of the tonic EMG activity was observed (43 to 50%), together with a great increase of the inocclusion space (X = 8.90 mm).